Various methods and systems were available for assisting a driver to operate a vehicle. One example of such systems is proposed in US 2003/0060936 A1, published Mar. 27, 2003 (application Ser. No. 10/226,232). This system comprises a controller, at least one actuator, and a data acquisition system for acquiring data related to a vehicle and environment in a field around the vehicle. The controller determines a future environment in the field around the vehicle using the acquired data, and generates an operator response plan in response to the determined future environment. The plan prompts the operator to operate the vehicle in a desired manner. The actuator is coupled to a driver controlled input device to mechanically affect operation of the input device in a manner that prompts, via a haptic input to the driver to operate the vehicle in the desired manner.
Another example of conventional driving assistance systems is proposed in JP10-166890. The system alters setting of a reaction force applied to a driver of a host vehicle via an accelerator pedal based on a distance between the host vehicle and the preceding vehicle. According to this system, a decrease in the distance causes an increase in the reaction force to convey information related to the reduced distance to the driver.
These known systems do not transmit a change in the status of the preceding vehicle to the driver at appropriate timing via the reaction force applied to the accelerator pedal, due to calculation delays by a controller to alter the reaction force and delays in the driver's recognition of the status change caused by the calculation delays. Consequently, the driver cannot perceive the changed status of the preceding vehicle soon enough via the reaction force applied to the acceleration pedal.
Accordingly, there is a need for a method and system for use in a host vehicle to convey information related to a future variation of a relative spatial relationship between the host vehicle and another vehicle, even before the actual variation occurs. There is another need for a system and method to transmit a change in an inter-vehicle distance between the host vehicle and other vehicles before the distance actually decreases.